1. Field of the Invention
The invention relates to a position sensor including at least two sensor units which measure in a contactless manner and whose sensor signals constitute similar, mutually phase-shifted functions of the position x to be measured relative to a movable element, and also including a phase detection unit for forming a position sensor signal which is a measure of the position x.
2 Discussion of the Related Art
Position sensors are used, for example for determining an angle of an element which is arranged so as to be rotatable with respect to the sensor units, or for determining the longitudinal position of an element which is slidable with respect to the sensor elements.
A position sensor for determining an angle .alpha. is known from EP-B 217 478. Therein, two sensor units which are constructed as magnetic films are fed, via two switches, with two 90.degree. phase-shifted sinusoidal alternating current signals from a sine-wave generator. The measured output voltages of the two magnetic films are separately applied, via a respective switch, to a comparator whose output is connected to a signal processing device for calculating the angle .alpha..
In the above arrangement measuring inaccuracies occur because of phase and amplitude errors of the sinusoidal input signals of the sensor units. A further problem consists in the separate feeding of the two output signals of the sensor units. On the one hand, any amplifiers and filters present in each channel do not have exactly the same gain and filter characteristic and on the other hand errors due to unequal weighting of the two output signals upon combination could degrade the measuring accuracy.